This application proposes a comprehensive training and research program focused on patient safety in transfusion medicine. The overall purpose of the proposed program is to provide skills and experience required for the development of an independent research career in health services research. The candidate is a critical care physician with a proven track record of commitment to training and research productivity who requires protected time to acquire further methodological expertise and to conduct a focused program of research. A rigorous calendar of formal course work, focused training, and on-going mentoring/collaboration is described. The research project proposed here uses a mixed methodology of quantitative and qualitative methods applied to the problem of blood product transfusion safety in children, similar to other low-frequency, high risk events. This approach will both capitalize on the education and experience of the candidate and allow specific enhancement of his skills in qualitative research, hierarchical modeling, and probabilistic risk assessment. Analyses of the Healthcare Cost and Utilization dataset and the Pediatric Healthcare Information Systems datasets will comprise the quantitative elements of the project. An analysis of the Medical Event Reporting System for Transfusion Medicine will complement the information derived in this component. The qualitative analysis will consist of an in-depth, cross institution, case study that will help to refine the quantitative information. The quantitative and qualitative components will then be used to inform a probabilistic risk assessment (PRA) model for blood product transfusions in children. PRA is a tool that is a hybrid between process analysis and decision support methods used in high-risk industries. It will be used to investigate blood product transfusions in healthcare and to determine its applicability for investigating other low-frequency, high risk patient safety problems.